Acrylonitrile butadiene styrene (ABS) is a common thermoplastic polymer known for its lightness, stiffness, scratch resistance and toughness. It is known to make sit-on-top kayaks of thermoformed ABS plastic. Commercially, kayaks of this manufacture are available from several companies, including Hurricane Kayaks, of Warsaw, N.C., website: hurricaneaquasports.com. The ABS kayak hulls are formed in two major pieces, a thermoformed top deck and thermoformed bottom. The deck and bottom are seamed together forming a hollow hull. ABS kayaks are lighter in weight than comparably sized polyethylene kayaks and also stiffer and more scratch resistant than polyethylene kayaks, however they do not have the same impact strength as polyethylene kayaks.
It is also known to install propulsion devices such as pedal drives or motor drives amidships of a rotomolded polyethylene kayak. Examples of such propulsion devices are seen in prior US Patent publication US20160075420 to Kiffmeyer and US20090042461 to Walton, the disclosures of which are incorporated herein by reference. These types of propulsion device installations are only known to be in kayaks made of polyethylene. Polyethylene is a plastic of high durability and impact strength but low hardness and rigidity. It feels waxy when touched.
It has been found that propulsions systems like the ones described in the published patent applications of Walton and Kiffmeyer cannot be satisfactorily installed in thermoformed ABS kayaks, as the stresses imposed on the hull and deck by the propulsion system are too great for the ABS to sustain over time without the potential for cracking.
Accordingly, there is a need in the art to be able to add a propulsion device to a kayak made of ABS plastic.